Nad p

(Z/E)-3’’-hydroxy-geranylhydroquinone [(Z/E)-3’’-OH-GHQ] was chemically synthesized as described previously (Oshikiri et al., 2020 (link)). Cofactors FMN, NAD(P)⁺ and NAD(P)H were purchased from Solarbio (Beijing, China). Deuterium oxide and the substrates cinnamyl alcohol, p-coumaryl alcohol, coniferyl alcohol, sinapyl alcohol, and geraniol were purchased from Macklin (Shanghai, China).

The root activity of tomato was determined with the triphenyltetrazolium chloride (TTC) method as previously described [45 (link)].
The activities of 6PGDH, G6PDH, NADP-IDCH and NADP-ME were measured by spectrophotometry, recording the reduction of NADP at 340 nm [46 (link), 47 (link)]. The experiment was conducted at 25 °C, and the reaction system volume was 1 ml, including 50 mM HEPES (pH 7.6, Solarbio, Beijing, China), 2 mM MgCl₂ (Sinopharm Chemical Reagent, Shanghai, China), 0.8 mM NADP (Solarbio, Beijing, China) and plant samples. The reaction was initiated by adding 5 mM 6-phosphate gluconate (Aladdin, Shanghai, China), 5 mM glucose 6-phosphate (Solarbio, Beijing, China), 10 mM 2R,3S-isocitrate (Aladdin, Shanghai, China) and 10 mM malic acid (Solarbio, Beijing, China), respectively.